U.S. patent application number 15/734638 was filed with the patent office on 2021-07-29 for variable frequency drive thermal management.
The applicant listed for this patent is CARRIER CORPORATION. Invention is credited to Ismail Agirman, Timothy M. Remmers.
Application Number | 20210234497 15/734638 |
Document ID | / |
Family ID | 1000005556538 |
Filed Date | 2021-07-29 |
United States Patent
Application |
20210234497 |
Kind Code |
A1 |
Agirman; Ismail ; et
al. |
July 29, 2021 |
VARIABLE FREQUENCY DRIVE THERMAL MANAGEMENT
Abstract
A system and method for thermal management in a variable
frequency drive is provided. Aspects include receiving, by a
processor, operational data associated with a variable frequency
drive, the operational data including one or more operational
parameters for the variable frequency drive, comparing the one or
more operational parameters to a threshold, and operating the
variable frequency drive to produce a first modulated output based
at least in part on the one or more operational parameters being
below the threshold.
Inventors: |
Agirman; Ismail;
(Southington, CT) ; Remmers; Timothy M.;
(Glastonbury, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CARRIER CORPORATION |
Palm Beach Gardens |
FL |
US |
|
|
Family ID: |
1000005556538 |
Appl. No.: |
15/734638 |
Filed: |
October 29, 2019 |
PCT Filed: |
October 29, 2019 |
PCT NO: |
PCT/US2019/058497 |
371 Date: |
December 3, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62755742 |
Nov 5, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02P 29/68 20160201;
H02P 27/08 20130101 |
International
Class: |
H02P 29/68 20060101
H02P029/68; H02P 27/08 20060101 H02P027/08 |
Claims
1. A method for thermal management in a variable frequency drive,
the method comprising: receiving, by a processor, operational data
associated with a variable frequency drive, the operational data
comprising one or more operational parameters for the variable
frequency drive; comparing the one or more operational parameters
to a threshold; and operating the variable frequency drive to
produce a first modulated output based at least in part on the one
or more operational parameters being below the threshold.
2. The method of claim 1, further comprising: operating the
variable frequency drive to produce a second modulated output based
at least in part on at least one of the one or more operational
parameters exceeding the threshold.
3. The method of claim 1, wherein the first modulated output
comprises a space vector pulse width modulation (SVPWM) output.
4. The method of claim 2, wherein the second modulated output
comprises a discontinuous pulse width modulation (DPWM) output.
5. The method of claim 2, wherein the second modulated output is
produced by the variable frequency drive for a first time
period.
6. The method of claim 5, further comprises: operating the variable
frequency drive to produce the first modulated output in response
to an expiration of the first time period.
7. The method of claim 1, wherein the one or more operational
parameters comprise a temperature parameter and a voltage
modulation parameter.
8. The method of claim 2, wherein the second modulated output is
produced by the variable frequency drive until the at least one or
the one or more operational parameters is below the threshold.
9. The method of claim 8, further comprising: operating the
variable frequency drive to produce the first modulated output in
response to the at least one of the one or more operational
parameters being below the threshold.
10. The method of claim 2, further comprising: monitoring the
operational data associated with the variable frequency drive to
determine a rate of change to the one or more operational
parameters; operating the variable frequency drive to produce the
second modulated output for a second time period, wherein the
second period of time is based at least in part on the rate of
change to the one or more operational parameters; and operating the
variable frequency drive to produce the first modulated output in
response to an expiration of the second time period.
11. A system comprising: a variable frequency drive; a sensor
configured to collect operational data associated with the variable
frequency drive; and a controller configured to: receive, from the
sensor, operational data, the operational data comprising one or
more operational parameters for the variable frequency drive;
compare the one or more operational parameters to a threshold; and
operate the variable frequency drive to produce a first modulated
output based at least in part on the one or more operational
parameters being below the threshold.
12. The system of claim 11, wherein the controller is further
configured to: operate the variable frequency drive to produce a
second modulated output based at least in part on at least one of
the one or more operational parameters exceeding the threshold.
13. The system of claim 11, wherein the first modulated output
comprises a space vector pulse width modulation (SVPWM) output.
14. The system of claim 12, wherein the second modulated output
comprises a discontinuous pulse width modulation (DPWM) output.
15. The system of claim 12, wherein the second modulated output is
produced by the variable frequency drive for a first time
period.
16. The system of claim 15, wherein the controller is further
configured to: operate the variable frequency drive to produce the
first modulated output in response to an expiration of the first
time period.
17. The system of claim 11, wherein the one or more operational
parameters comprise a temperature parameter and a voltage
modulation parameter.
18. The system of claim 12, wherein the second modulated output is
produced by the variable frequency drive until the at least one of
the one or more operational parameters is below the threshold.
19. The system of claim 18, wherein the controller is further
configured to: operate the variable frequency drive to produce the
first modulated output in response to the at least one of the one
or more operational parameters being below the threshold.
20. The system of claim 12, wherein the controller is further
configured to: monitor the operational data associated with the
variable frequency drive to determine a rate of change to the one
or more operational parameters; operate the variable frequency
drive to produce the second modulated output for a second time
period, wherein the second period of time is based at least in part
on the rate of change to the one or more operational parameters;
and operate the variable frequency drive to produce the first
modulated output in response to an expiration of the second time
period.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Application No.
62/755,742, filed on Nov. 5, 2018, which is incorporated herein by
reference in its entirety.
BACKGROUND
[0002] Exemplary embodiments pertain to the art of variable
frequency drives and more specifically to variable frequency drive
thermal management for HVAC/Chiller systems.
[0003] Heating, ventilation, and air-conditioning (HVAC) and
chiller systems, typically, utilize a variable frequency drive
(VFD) to operate certain components of these systems. A VFD is a
type of adjustable-speed drive used in electro-mechanical drive
systems to control AC motor speeds and torque by varying motor
input frequency and voltage. For HVAC and chiller systems, VFDs can
utilize a standard space vector pulse width modulation (SVPWM) to
control a motor input frequency and voltage. This standard SVPWM is
utilized for acoustic and smooth operation considerations. However,
VFDs can suffer from thermal trip when utilizing SVPWM and when
exposed to extreme load conditions with high modulation indexes and
high load conditions.
BRIEF DESCRIPTION
[0004] Disclosed is a system. The system includes a variable
frequency drive, a sensor configured to collect operational data
associated with the variable frequency drive, and a controller
configured to receive, from the sensor, operational data, the
operational data including one or more operational parameters for
the variable frequency drive, compare the one or more operational
parameters to a threshold, and based on the one or more operational
parameters being below the threshold, operate the variable
frequency drive to produce a first modulated output.
[0005] In addition to one or more of the features described above,
or as an alternative, further embodiments of the system may include
that the controller is further configured to, based on at least one
of the one or more operational parameters exceeding the threshold,
operate the variable frequency drive to produce a second modulated
output.
[0006] In addition to one or more of the features described above,
or as an alternative, further embodiments of the system may include
that the first modulated output includes a space vector pulse width
modulation (SVPWM) output.
[0007] In addition to one or more of the features described above,
or as an alternative, further embodiments of the system may include
that the second modulated output includes a discontinuous pulse
width modulation (DPWM) output.
[0008] In addition to one or more of the features described above,
or as an alternative, further embodiments of the system may include
that the second modulated output is produced by the variable
frequency drive for a first time period.
[0009] In addition to one or more of the features described above,
or as an alternative, further embodiments of the system may include
that the controller is further configured to operate the variable
frequency drive to produce the first modulated output in response
to an expiration of the first time period.
[0010] In addition to one or more of the features described above,
or as an alternative, further embodiments of the system may include
that the one or more operational parameters includes a temperature
parameter (sensor) and a voltage command (modulation index)
parameter.
[0011] In addition to one or more of the features described above,
or as an alternative, further embodiments of the system may include
that the controller is further configured to operate the variable
frequency drive to produce the first modulated output in response
to the at least one of the one or more operational parameters being
below the threshold.
[0012] In addition to one or more of the features described above,
or as an alternative, further embodiments of the system may include
that the controller is further configured to monitor the
operational data associated with the variable frequency drive to
determine a rate of change to the one or more operational
parameters, operate the variable frequency drive to produce the
second modulated output for a second time period, wherein the
second period of time is based at least in part on the rate of
change to the one or more operational parameters, and operate the
variable frequency drive to produce the first modulated output in
response to an expiration of the second time period.
[0013] Disclosed is a method for thermal management. The method
includes receiving, by a processor, operational data associated
with a variable frequency drive, the operational data including one
or more operational parameters for the variable frequency drive,
comparing the one or more operational parameters to a threshold,
and based on the one or more operational parameters being below the
threshold, operating the variable frequency drive to produce a
first modulated output.
[0014] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
based on at least one of the one or more operational parameters
exceeding the threshold, operating the variable frequency drive to
produce a second modulated output.
[0015] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
that the first modulated output includes a space vector pulse width
modulation (SVPWM) output.
[0016] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
that the second modulated output includes a discontinuous pulse
width modulation (DPWM) output.
[0017] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
that the second modulated output is produced by the variable
frequency drive for a first time period.
[0018] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
operating the variable frequency drive to produce the first
modulated output in response to an expiration of the first time
period.
[0019] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
that the one or more operational parameters includes a temperature
(heat sink sensor feedback) parameter and a voltage command to the
motor as the output of the inverter or in other words the
modulation index parameter of the PWM generation action.
[0020] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
that the second modulated output is produced by the variable
frequency drive until the at least one or the one or more
operational parameters is below the threshold.
[0021] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
operating the variable frequency drive to produce the first
modulated output in response to the at least one of the one or more
operational parameters being below the threshold.
[0022] In addition to one or more of the features described above,
or as an alternative, further embodiments of the method may include
that monitoring the operational data associated with the variable
frequency drive to determine a rate of change to the one or more
operational parameters, operating the variable frequency drive to
produce the second modulated output for a second time period,
wherein the second period of time is based at least in part on the
rate of change to the one or more operational parameters, and
operating the variable frequency drive to produce the first
modulated output in response to an expiration of the second time
period.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The following descriptions should not be considered limiting
in any way. With reference to the accompanying drawings, like
elements are numbered alike:
[0024] FIG. 1 depicts a block diagram of a refrigerant vapor
compression system for use in implementing one or more embodiments;
and
[0025] FIG. 2 depicts a flow diagram of a method for thermal
management in a variable frequency drive according to one or more
embodiments;
[0026] FIG. 3 depicts a flow diagram of a method for thermal
management in a variable frequency drive according to one or more
embodiments; and
[0027] FIG. 4 depicts a graphical representation of a DPWM and SPWM
wave form according to one or more embodiments.
[0028] The diagrams depicted herein are illustrative. There can be
many variations to the diagram or the operations described therein
without departing from the spirit of the disclosure. For instance,
the actions can be performed in a differing order or actions can be
added, deleted or modified. Also, the term "coupled" and variations
thereof describes having a communications path between two elements
and does not imply a direct connection between the elements with no
intervening elements/connections between them. All of these
variations are considered a part of the specification.
DETAILED DESCRIPTION
[0029] Referring to FIG. 1, there is shown a refrigerant vapor
compression system 50 having a variable speed compressor 52 driven
by a variable speed motor 68 according to one or more embodiments.
The system 50 includes refrigerant vapor from compressor 52 that is
delivered to a condenser 54 where the refrigerant vapor is
liquefied at high pressure, thereby rejecting heat to the outside
air. The liquid refrigerant exiting condenser 54 is delivered to an
evaporator 58 through an expansion valve 56. In embodiments, the
expansion valve 56 may be a thermostatic expansion valve or an
electronic expansion valve for controlling super heat of the
refrigerant. The refrigerant passes through the expansion valve 56
where a pressure drop causes the high-pressure liquid refrigerant
to achieve a lower pressure combination of liquid and vapor. As the
indoor air passes across evaporator 58, the low-pressure liquid
refrigerant absorbs heat from the indoor air, thereby cooling the
air and evaporating the refrigerant. The low-pressure refrigerant
is again delivered to compressor 52 where it is compressed to a
high-pressure, high temperature gas, and delivered to condenser 54
to start the refrigeration cycle again. It is to be appreciated
that while a specific refrigeration system is shown, the present
teachings are applicable to any heating or cooling system,
including a heat pump, HVAC, and chiller systems. In a heat pump,
during cooling mode, the process is identical to that as described
hereinabove, while in the heating mode, the cycle is reversed with
the condenser and evaporator of the cooling mode acting as an
evaporator and condenser, respectively.
[0030] Turning now to an overview of technologies that are more
specifically relevant to aspects of the disclosure, the system 50
includes a compressor 52 driven by an inverter drive 62. In
embodiments, the inverter drive 62 may be a variable frequency
drive (VFD) or a brushless DC motor (BLDC) drive. Particularly,
inverter drive 62 is operably coupled to compressor 52, and
receives an alternating current (AC) electrical power (for example,
electrical power is a single-phase AC line power at 230V/60 Hz)
from a power supply 60 and outputs electrical power on line 66 to a
variable speed motor 68. The variable speed motor 68 provides
mechanical power to drive a crankshaft of the compressor 62. In an
embodiment, the variable speed motor 68 may be integrated inside
the exterior shell of the compressor 62. Inverter drive 62 includes
solid-state electronics to modulate the frequency of electrical
power on line 66. In an embodiment, inverter drive 62 converts the
AC electrical power, received from supply 60, from AC to direct
current (DC) using a rectifier, and then converts the electrical
power from DC back to a pulse width modulated (PWM) signal, using
an inverter, at a desired PWM frequency in order to drive the motor
68 at a motor speed associated with the PWM DC frequency. For
example, inverter drive 62 may directly rectify electrical power
with a full-wave rectifier bridge, and may then chop the electrical
power using insulated gate bipolar transistors (IGBT's) or
thyristors to achieve the desired PWM frequency. In embodiments,
other suitable electronic components may be used to modulate the
frequency of electrical power from power supply 60. Further,
control unit 64 includes a processor for executing an algorithm
used control the PWM frequency that is delivered on line 66 to the
motor 68. By modulating the PWM frequency of the electrical power
delivered on line 66 to the electric motor 68, control unit 64
thereby controls the torque applied by motor 68 on compressor 52
there by controlling its speed, and consequently the capacity, of
compressor 52. Also shown, the control unit (controller) 64
includes a computer readable medium for storing data in a memory
unit related to estimating compressor discharge pressure from
compressor and refrigeration system parameters. In embodiments, the
control unit 64 stores information related to compressor torque as
well as line voltages, compressor motor current, and compressor
speed obtained from inverter drive 62.
[0031] In one or more embodiments, the variable speed drive
(inverter) 62 can utilize a standard space vector PWM (SVPWM) for
acoustic and smooth operation reasons when driving the variable
speed motor 68 in the system 50. However, as mentioned above,
operating with a SVPWM under extreme load conditions can cause
thermal trip within the VFD 62. In one or more embodiments, a heat
sink and a sensor can be utilized to address thermal trip by the
control unit 64 monitoring the heat sink temperature using the
sensor. When the temperature approaches to thermal trip level
(e.g., threshold temperature, for example, 90 degrees Celsius), the
VFD can switch to a discontinuous PWM (DPWM) for a set or variable
time period or until the heat sink temperature returns to below the
threshold temperature. After the expiration of this time period in
DPWM mode of operation, the VFD can resume back to the SVPWM mode
if the margin from the thermal trip is large. In one or more
embodiments, the reason for remaining at the DPWM mode for a set
period of time is to avoid chattering of DPWM and standard SVPWM
causing irregular and noticeable acoustic noise.
[0032] In one or more embodiments, a second condition, besides
thermal trip, can be utilized when switching to DPWM mode in the
VFD. This second condition includes a voltage modulation index. For
example, when the modulation index is above 85%-90%, is added to
the decision for switching to DPWM. The reason for this second
condition in the decision is to avoid excessive PWM ripple in the
variable speed motor 68 which can cause increased noise level from
the variable speed motor 68 and also increases motor losses.
[0033] In one or more embodiments, when switching to the DPWM mode,
the control unit 64 can keep the VFD 62 in this DPWM mode until the
operational conditions (e.g., temperature and voltage command or
modulation index) are below the threshold temperature and threshold
voltage modulation. Once the operational conditions return to below
the threshold levels, the control unit 64 can operation the VFD 62
to produce the SVPWM output. In one or more embodiments, the VFD 62
is operated in the DPWM mode for a time period. Also, the control
unit 64 can monitor the operational conditions, through the sensor,
to determine a rate of change to the operational conditions. For
example, if the temperature is slowly falling, the control unit 64
can determine the rate of change and set a time period for when to
switch back to SVPWM mode.
[0034] FIG. 2 depicts a flow diagram of a method for thermal
management in a variable frequency drive according to one or more
embodiments. The method 200 includes receiving, by a processor,
operational data associated with a variable frequency drive, the
operational data comprising one or more operational parameters for
the variable frequency drive, as shown in block 202. At block 204,
the method 200 includes comparing the one or more operational
parameters to a threshold. And based on the one or more operational
parameters being below the threshold, the method 200 includes
operating the variable frequency drive to produce a first modulated
output, as shown at block 206. And at block 208, the method 200
includes, based on at least one of the one or more operational
parameters exceeding the threshold, operating the variable
frequency drive to produce a second modulated output.
[0035] Additional processes may also be included. It should be
understood that the processes depicted in FIG. 2 represent
illustrations and that other processes may be added or existing
processes may be removed, modified, or rearranged without departing
from the scope and spirit of the present disclosure.
[0036] FIG. 3 depicts a flow diagram of a method for thermal
management in a variable frequency drive according to one or more
embodiments. In one or more embodiments, the method 300 begins at
decision block 302 that is monitoring operational conditions to
determine that the operational conditions exceed a threshold
operating condition. The operating conditions being monitored
include, but are not limited to, the inverter heat sink temperature
312 and the inverter phase voltage 314. For example, if the heat
sink temperature exceeds 90 degrees C. (threshold temperature) then
the decision block moves to process step 304. At process step 304,
the method 300 switches the operational frequency of the inverter
to the DPWM mode. While in DPWM mode, a timer can be set and the
operational conditions can be continued to be monitored. When the
timer expires, at decision block 306, the operational conditions
are analyzed. In one or more embodiments, the timer can be set to a
longer time period than needed for the VFD heat sink cool down
time. Having a set time longer than needed for the heat sink to
cool down avoids a cyclic nature of entering and exiting the DPWM
mode which can cause customer discomfort with the HVAC system due
to noise. In one or more embodiments, the timer can have varying
minimum time periods when entering DPWM mode to avoid a cyclic
change. At decision block 308, when both the timer has expired and
the operational conditions are below the threshold, the method 300
proceeds to process block 310 and switches back to SVPWM for the
inverter. If the timer is not expired or the operational conditions
are above the threshold, the inverter remains in DPWM mode.
[0037] FIG. 4 depicts a graphical representation of a DPWM and SPWM
wave form according to one or more embodiments. The graphical
representation 400 includes a wave form for the SVPWM mode 402 and
the DPWM mode 404.
[0038] A detailed description of one or more embodiments of the
disclosed apparatus and method are presented herein by way of
exemplification and not limitation with reference to the
Figures.
[0039] The term "about" is intended to include the degree of error
associated with measurement of the particular quantity based upon
the equipment available at the time of filing the application.
[0040] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the present disclosure. As used herein, the singular forms "a",
"an" and "the" are intended to include the plural forms as well,
unless the context clearly indicates otherwise. It will be further
understood that the terms "comprises" and/or "comprising," when
used in this specification, specify the presence of stated
features, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, integers, steps, operations, element components, and/or
groups thereof.
[0041] While the present disclosure has been described with
reference to an exemplary embodiment or embodiments, it will be
understood by those skilled in the art that various changes may be
made and equivalents may be substituted for elements thereof
without departing from the scope of the present disclosure. In
addition, many modifications may be made to adapt a particular
situation or material to the teachings of the present disclosure
without departing from the essential scope thereof. Therefore, it
is intended that the present disclosure not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this present disclosure, but that the present
disclosure will include all embodiments falling within the scope of
the claims.
* * * * *